The present disclosure relates to a developing device supplying a developer to an image carrier and an image forming apparatus including this.
Generally, an electrographic image forming apparatus emits a light based on image information to a circumference face of a photosensitive drum to form an electrostatic latent image. The image forming apparatus supplies a toner from a developing device to this electrostatic latent image to form a toner image, transfers the toner image onto a sheet, and then, carries out fixing process, thereby forming an image.
The developing device applied in the general image forming apparatus includes a case, a screw, a developing roller and a sensor. The screw conveys and agitates a developer contained in the case. The developing roller carries the developer and supplies it to the photosensitive drum. The sensor detects a developer amount in the case. The developer not supplied to the photosensitive drum when developing is returned into the case, agitated by the screw and used for developing, again.
If a deteriorated toner is adhered onto the screw, agitating and conveying functions of the screw are lowered. Therefore, in the general developing device, due to occurrence of charging failure of the developer in the case, sufficient developer cannot be conveyed to a developing roller or the like and image failure occurs.
For example, there is a developing device including a collision member colliding with a center part in an axis direction of a rotating supply chamber screw blade member. The developing device makes the collision member collide to vibrate the supply chamber screw blade member and to shake the deteriorated developer (toner) adhered onto the supply chamber screw blade member
The above-mentioned developing device cannot provide strong vibration to an end part in the axis direction of the supply chamber screw blade member not colliding with the collision member. Therefore, in the end part in the axis direction of the supply chamber screw blade member, the developer adhered onto a rotation shaft of the supply chamber screw blade member agglomerates to cause so-called shaft thickening. When the shaft thickening occurs, the supply chamber screw blade member cannot suitably carry out developer conveyance. According to this, a conveyance amount of the developer is decreased. At this time, the sensor erroneously detects the decrease of the conveyance amount of the developer as the decrease of the developer amount even through the developer amount is not varied. Therefore, the above-mentioned developing device has a problem of not suitably maintaining the developer amount in the case.